1. Field of the Invention
The present invention relates to a medical instrument holding device for holding a treating device, endoscope or the like used in surgical operation.
2. Description of the Related Art
In recent years, in the field of surgical operation a variety of medical instruments such as observation devices and treating devices are increasingly being used for surgical operation. For example, an endoscope is used to observe the rear side of an operation site that an operator could not see directly by means of a microscope for operation. Moreover, supersonic waves are often used in inspections for confirming the internal structure of tissue scheduled to be surgically incised.
In the surgical operation, in general, a patient is laid on an operating table, and an operator positions by the side of the patient to carry out required surgical treatment in the operation site of the patient. In this case, a lumen provided at the surface of the patient by surgical incision has a spatial peculiarity that the longitudinal direction of the “hole” of the lumen substantially coincides with the direction of the gravity. Such a relation between the lumen and the gravity is necessarily realized from the arrangement between the patient and the operator.
As the surgical operation is proceeding in such a positional relation, a situation can occur that the operator must hold the medical instrument for a long period of time. In order to preclude this undesirable though possible situation, a wide variety of holding devices have been proposed to reduce operator's burden. For example, a holding device having a plurality of arms connected by articulations is typical. In this device, either of fixed and release conditions of the articulations can be selected by operation of an operator. After the operator has moved a medical instrument to a desired position under the released condition, he brings it into the fixed condition and makes the holding device support the medical instrument at the desired position.
As such a medical instrument holding device, for example, Jpn. Pat. Appln. KOKAI Publication No. 8-052158, U.S. Pat. No. 4,863,133, U.S. Pat. No. 5,170,790 and WO 95/10985 disclose devices using ball joint elements at articulations to realize a miniaturization of device, respectively.
In Jpn. Pat. Appln. KOKAI Publication No. 6-113997 proposed by the applicant of the present application, a medical instrument holding device with a counter balancing system is disclosed. According to this holding device, even when an arm is under a released condition, by balancing the weight of a medical instrument itself held by the device and another weight, the medical instrument can be held without any burden applying to an operator. Therefore, it is possible for the operator to disregard the weight of the medical instrument and to do its movement.
Moreover, Jpn. Pat. Appln. KOKAI Publication No. 2001-258903 discloses a holding device employing a counter balancing system with links and using a ball joint element at one moving portion arranged at leading end of an arm. In this device, the leading end of the arm to be positioned in the proximity of an operating position is miniaturized by a ball joint element. As shown in FIG. 13A of the disclosed Application, further when the insertion shaft of an endoscope 61 is substantially horizontal, a balance can be ensured. This is because the center of a gravity G of the grasping portion 63 having an endoscope 61 mounted thereon is arranged substantially in the vertical line passing through the spherical center of the ball joint element 62 or center Ob of rotation of the ball joint element 62.
In the device disclosed in Jpn. Pat. Appln. KOKAI Publication No. 8-052158, U.S. Pat. No. 4,863,133, U.S. Pat. No. 5,170,790 or WO 95/10985, although the miniaturization is realized by the use of ball joint elements at the articulations, structural parts become unbalanced during movement. Therefore, the operator must eliminate this unbalance by himself by holding a structural part, for example, the grasping portion, so that the operability is degraded when requiring delicate operation.
In the device disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-113997 mentioned above, as the arm portion moves as a whole when moving a medical instrument, it can be held always under balanced condition, whereas the arm would interfere with an operator. In operation in cranial nerve surgery, particularly, as various devices used in an operation are concentrically arranged at an operation site in a lumen, there is a requirement for a miniaturization of the arm itself so as to be freely moved and held in a narrow moving space.
In the device disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2001-258903, moreover, when an operator actually uses the device in an operation, the insertion shaft of the endoscope 61 is used in the direction substantially coinciding with the direction of the gravity as shown in FIGS. 13B and 13C. Under the released condition of the ball joint element 62, however, the weight applied to the point G would fall in the direction M with respect to the point Ob. In other words, under this condition, an unbalanced state would occur and the operator would have to support by himself the weight of the endoscope 61 applying to the grasping portion 63, thereby resulting in degraded operability.
In the medical instrument holding devices of the prior art, as the arms in the proximity of operating position become bulky, they would interfere with the operation. Moreover, under the released condition of the arm, the operator has to move (or operate) the grasping portion and the medical instrument under an unbalanced condition that the center of gravity of the grasping portion and medical instrument thereon is shifted from the desired position, whereby the operability of the holding device is degraded. These problems would cause affection of an operator and complicate the work operation of the operator, resulting in a lower operation efficiency.